New science on the dairy water footprint

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Source: Dairy Research Blog

A water footprint for dairy is a new way of measuring the amount of water used per litre of milk produced. It’s used to benchmark performance in sustainability and help farmers measure the impacts of their actions to improve water conservation and preservation.

Conserving water not only helps improve farm sustainability, it benefits a dairy farm operation by:

  • Saving electricity through less pumping water and heating water for cleaning;
  • Reducing costs for treating water – depending on water quality, this can be a big factor; and,
  • Lowering fuel costs – reducing water in manure storage means less to transport from the storage to the field for application.

Water use

VanderZaag’s team measured water use in different dairy farms (tie-stall, freestall and robotic milking) in Ontario. They found that for milking system cleaning, the average daily water use was:

  • ~75 litres/day/cow [i]for an automatic milk system
  • ~30 litres/day/cow for a tie-stall parlour
  • ~21 litres/day/cow for a free-stall parlour

They also observed that:

  • Robotic milking systems use more water per cow than parlours and tie‐stall milking systems;
  • Drinking water consumption is highly correlated with the maximum air temperature – therefore minimizing heat stress to animals can reduce the water footprint of milk by reducing water demand and increasing milk production;
  • Water leaks around the farm can lead to significant water losses;
  • Water loss can be minimized at drinking fountains by preventing overflow due to faulty float control and poorly levelled tanks;
  • Reusing water can help reduce water consumption, for example, plate‐cooler water can be fully recuperated;
  • In a case study of two farms (one free-stall and one tie-stall), the water footprint was calculated as a range of 4 to 7 litres of water per litre of milk produced.

Water and nutrient losses

VanderZaag and his collaborators measured water and nutrient losses for several years at experimental sites near Ottawa using sophisticated instruments to measure water loss into the air, through tile drains, milkhouse effluent and treatment, and the timing of manure application. They used models based on the measurements to evaluate farm management scenarios for their effect on the water footprint and options to reduce it.

The researchers found that:

  • On a whole‐farm basis, over 99% of all water loss from dairy farming is from crops and pastures, with the remaining loss from cattle intake;
  • Spring application of manure reduces nitrogen leaching compared to fall application;
  • Split applications between planting and side‐dress can further increase nitrogen-efficiency if the application rate is matched to crop requirements;
  • Spring applications (before planting, or split before and after emergence) were beneficial at all nitrogen application rates;
  • Increasing alfalfa in rotation led to less polluted water and nitrate leaching, and less nitrogen-leached per unit of nitrogen‐yield, but overall yield slightly declined.

How to conserve and preserve water – NEW Fact sheets available!

Two new fact sheets produced by Dairy Farmers of Canada in consultation with Dr. VanderZaag are now available for information on efficient water use under the proAction program and help farmers in their efforts for continued sustainability improvements. You can download the fact sheets here: DairyResearch.ca.